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Cam and Crank Sensor Testing

I just had the motor rebuilt for my 1997 GMC K1500 (350 Vortec). After installing it into the truck - it will not start! My timing light shows that I am getting spark. If I shoot some starting fluid into the air cleaner housing, it will attempt to run.

There is nothing more disappointing or frustrating than a new engine that will not start!

I made a noid light out of an old taillight bulb, and I get nothing from every pin pair in the connector. I checked the cam position sensor (CMP) and the crank position sensor (CKP) using the procedure in your manual (24065, pages 6-15 and 6-16) and I get similar behavior from both. If I follow the book procedure to backprobe the signal (I used a paperclip) with the positive lead of my meter and connect the negative to a ground - I never get past 0.25 VAC on the CMP and 0.6 VAC on the CKP. If I backprobe the signal output and and attach my meter's negative lead to the signal return on the connectors - I see about a lot of variety with a peak of 3.5 VAC from the CMP, and a pretty steady 2.5 VAC from the CKP. Both connectors have a good 12 volt supply between the pink wire and ground.

Does probing the connectors produce a valid result? Does the fact that I don't get a decent reading between the connector and ground indicate a wiring problem?

I'm not so sure your homemade 'noid light is a valid test. An actual 'noid light doesn't use a bulb, it uses an LED.

Since you're getting similar performance from the CMP and CKP sensors, I doubt if either of those are your problem. As far as the values you're getting, keep in mind that the manual states that those values are "approximate."

Fuel Injection Pain

I have a gauge on the port right now. When I turn the key on, the gauge peaks at 60-62 psi and then falls back to 56 when the pump goes off. I don't have the return blocked.

I tested each injector by keying the ignition on to pressurize the fuel system and then turning the key off. I then connected 12 volts to a pair of injector pins to see if the fuel pressure would drop. I repeated this procedure for each injector. Seven out of 8 injectors do drop the fuel pressure when energized, so I know I have 1 bad one.

I made the noid light with a bulb because the dealer I spoke with said that they use the 194 bulbs out of the marker light. I will make one out of one of my marker lights and try it again.

As mentioned in the prior post, if I shoot some starting fluid into the air cleaner box - it shows immediate signs of life.